$WD check

So...After years of drooling, I finally decided to by a Jeep.
Ended up with a 1999 model, Apparently, the previous owner liked it so much, that he installed a sunroof (I never seen an XJ with a sunroof and the manual does not mention it either, but might be wrong)
I would like to know what is the least painful method to check if my 4WD works.
The manual tells me that a light shout come on. I went tonight and drove on a bumpy gravel road and pulled the lever on 4HI, but the light did not come on. I did not hear anything unusual then stopped and floored it, but nothing happened, I mean tires did not spin and figured out that it is the tires. I just installed Revo's all terrain.
Thanks in advance

4WD, $WD....it's pretty much the same. Least painful is to get on loose dirt and punch it, or take it out wheeling and you'll be able to figure out whether it's working by the noise and performance (or lack thereof). Don't shift into 4wd on dry surfaces or rainy ones with good traction unless you've got a full-time t-case (NP242).

Sunroofs were offered as factory at one point, and I think were also a dealer option later but are pretty rare...

I have a sunroof on my '96 Classic (along w/manual doors/windows--interesting combination). The one or two sunny days we've had this spring ( have already persuaded me that I need to put a darker tint on it.

I'm also interested in the answers to your 4WD question though by '99 they might have discontinued the Command-Trac (part time) system I have. I just bought mine a month ago, haven't had a chance to test it, & have been wondering if I just have to trust that it will work when it's needed next winter. I've read my owner's manual instructions but am still a litle hazy about when to use LO & when/how to shift into HI.

I don't feel safe making any kind of change to the T-case when I'm moving on slick roads; afraid it might affect traction. Is this reasonable or foolish?

They certainly did offer suroofs from the factory although as near as I can tell it was on the earlier Chief models. It had a screw type opener and you have to take the screws out of the hinges to take it off competely. It is fairly large and has a nice tie-in to the roof pillar. I found one in the junkyard and couldn't resist taking it off. Now I just need the courage to cut out my roof and install it.

The most verifiable way is to put up in the air and engage 4WD, you should get at least one wheel in the front and one in the rear turning. Other method is to get in some sand or loose dirt. Engage 4WD and you will feel a difference especially on tight turns. Generally it will always work provided you don't have one of the vac front disconnects on the front axle. The disconnect is on the passenger side about midway between the pumpkin and passenger side front wheel, has a couple of vac hoses coming out of it but I'm pretty sure that they were not used after 90 or so. If you have a limited slip rear then BOTH rear tires will turn or with the engine turned off if you turn one wheel the other will turn in the same direction, if you don't have a limited slip the opposite wheel will turn in the opposite direction. Also look for a metal tag on the rear differential, that should also say LSD or 'use friction modifier' or something similar.

Thank you very much for your answers.
I am happy to report that the 4WD is working fine.
Had busy couple of weeks, but tonight I managed to go to one of the beaches around here. I choose a place right by the water where the bank was very steep and floored it. Had my wife watch for spinning. Then I got out and she did the experiment. Both front and rear tires spun, before gripped and then the Jeep took off. I declare success.
No, despite being Cherokee Sport 99, mine still has the command track and when I was buying, I was looking for one equipped with select track (mainly 2000-01 models),but the majority were part time only.
Once again, thank you for your answers
Ciao
P.S. What do you think, should I bother fixing the light? Is it easy to do and how much time would this take?

As you found out, the light on the dash has no bearing on whether or not 4 WD is engaged. The light is controlled by a vacuum actuated switch in the transfer case. Check to make sure that the light isn’t burned out. If that doesn’t fix your problem then most likely is a blocked/disconnected vacuum tube. It’s not worth opening up the transfer case just to fix that.